I know that SO is not a site for simply copy-paste one's code. But don't you think there should be a separate stack exchange site just for this, where people would be pasting their snippets of code and others would be rating or making suggestions to it ?
The point-reward system that is implemented in SE sites seems ideal for that. There is really no site that focuses on this problem, on many discussion board pasting code just for showing off is also discouraged, and other sites are focused on development and are addressed for skilled programmers.
Example question ideal for such site would be: how do you improve my function so it would be faster/ have less code. What programming error did I do coding this etc.
The key thing is that this site would be only for willing people that want to participate in this way. People who paste clever/ brilliant/ most understandable code for given problems and those who help in best way would be given more points.